Formal and Impersonal:
* Official: (coming from a recognized source)
* Definitive: (conclusive, final)
* Authoritative: (having the power to command)
* Legitimate: (lawful, valid)
* Credible: (believable, trustworthy)
* Valid: (sound, well-founded)
* Binding: (enforceable, obligatory)
* Decisive: (concluding, definitive)
Implying Expertise or Power:
* Expert: (knowledgeable, skilled)
* Competent: (able, qualified)
* Knowledgeable: (informed, well-versed)
* Dominant: (influential, powerful)
* Commanding: (influential, powerful)
* Influential: (having power, having effect)
* Leading: (principal, primary)
* Superior: (higher in rank, quality, or value)
Expressing Confidence and Conviction:
* Conclusive: (decisive, final)
* Definitive: (conclusive, final)
* Firm: (unwavering, resolute)
* Strong: (powerful, forceful)
* Assured: (confident, self-assured)
* Decisive: (concluding, definitive)
* Unwavering: (steadfast, resolute)
* Resolute: (determined, unwavering)
More Informal Synonyms:
* Weighty: (important, significant)
* Persuasive: (convincing, influential)
* Telling: (significant, revealing)
* Reliable: (dependable, trustworthy)
* Trustworthy: (reliable, dependable)
* Powerful: (strong, influential)
The best synonym will depend on the specific context and the nuance you want to convey.